1. Field of Invention
The present invention relates generally to data communication systems. More particularly, the present invention relates to systems and methods for enabling Ethernet that is transported over a SONET network to benefit from features such as tandem connection monitoring.
2. Description of the Related Art
The demand for data communication services is growing at an explosive rate. Much of the increased demand is due to the fact that more residential and business computer users are becoming connected to the Internet. Furthermore, the types of traffic being carried by the Internet are shifting from lower bandwidth applications towards high bandwidth applications which include voice traffic and video traffic.
The Ethernet protocol or data transport technology is widely used in local area networks (LANs). However, in larger networks such as metro area networks (MANs), SONET transmission systems are typically used. Hence, when data is transmitted from LANs onto MANs, service providers generally must manage the two different protocols, and effectively perform a translation between the two protocols. Service providers may have to configure equipment and services for transmitting data from LANs onto MANs, which may be an involved and expensive process.
Converged Data Link (CDL) is a protocol that provides Ethernet with operations, administration, and management capabilities which service providers generally expect from SONET. The use of Ethernet with CDL to move data over MANs effectively eliminates the need to conduct translation between the Ethernet protocol and the SONET protocol. Further, the need to configure equipment and services to accept both Ethernet and SONET may be substantially eliminated.
Since SONET transmission systems offers some desirable features that are not offered by Ethernet or by Ethernet with CDL, when Ethernet is used to transport data over a MAN instead of SONET, some of the desirable features may be lost. Tandem connection monitoring is one feature that is offered by SONET, as well as SDH, which is generally not available to Ethernet. The use of tandem connection monitoring generally enables transmission section error performance information to be provided across a plurality of domains or service provider networks, as will be appreciated by those skilled in the art. Hence, it is possible to determine the domain within which an error occurs.
FIG. 1 is a diagrammatic representation of a network which includes multiple domains. A network 100 may be split into domains 104. Each domain 104 includes network elements 108, e.g., a first domain 104a includes a network element 108a. When a path message 112 is to be sent from network element 108a, which is in first domain 104a, to a network element 108d in a third domain 104c, packets are sent through network elements 108b, 108c in a second domain 104b. 
When tandem connection monitoring is available in network 100, an operator or network administrator may evaluate performances of a sub-network or domain 104 within network 100, as mentioned above. Tandem connection monitoring is used in SONET and SDH networks to provide information on errors that arise within a network. When data is transferred through different domains 104 in network 100, monitoring the performances associated with each path segment 116 associated with path message 112 may be important, particularly when each domain 104 may be managed by a different operator. Using tandem connection monitoring enables the sources of errors and defects to be identified, thereby enabling modifications or corrections to be made to the sources to reduce the occurrence of errors and defects.
Since tandem connection monitoring is generally not available in an Ethernet protocol or an Ethernet with CDL protocol, it is generally not possible to monitor the performance of each path between different domains that is associated with an overall full path. In other words, it is typically not possible with an Ethernet protocol to determine where particular errors or defects are generated. Since Ethernet traffic is becoming more prevalent in MANs, the ability to provide tandem connection monitoring for an Ethernet protocol would be desirable.
Therefore, what is needed is a method and an apparatus for enabling tandem connection monitoring to be applied to Ethernet packets that are sent through a network. More specifically, what is desired is a system which allows tandem connection and performance monitoring of Ethernet signals.